1. Field of the Invention
The present invention relates to a digital TV set for receiving a multichannel television signal, and more particularly, to a method and apparatus for displaying channel information on a TV screen.
2. Description of the Related Art
In analog TV broadcasting such as an NTSC (National Television System Committee) system, only one program can be transmitted through a specified frequency band of an RF channel.
On the contrary thereto, in a digital TV broadcasting system for a next generation system such as an HDTV (High Definition TV), the number of RF channels is much greater than in the analog TV broadcasting system. Furthermore, the bit rate required can be allocated to a needed service when necessitated. That is, a plurality of programs can be transmitted over a limited transmission bandwidth of an RF channel. For example, the existing standard definition television (SDTV) programs such as analog TV broadcast can be planned on multichannels for a period of time, and the HDTV programs on a single channel for another time zone. Such an example is referred to as the ATSC (United States Advanced Television System Committee) Standard. According to the ATSC standard, it is recommended that subchannels of at least one HD program plus six SD programs at a maximum can be broadcast on an RF channel corresponding to an existing analog channel.
Besides, the number of subchannel programs transmitted through each RF channel can be also changed while a user is watching TV. For example, a TV broadcast with three SD programs can be additionally added by a further SD program, thereby being changed to a TV broadcast with four SD programs, and on the contrary, to a single HD program. For reference, since it hardly ever occurs that several programs are simultaneously added or terminated, it is assumed in most cases that one or another program is added or cancelled.
As described above, since multiple programs can be broadcast on a single RF channel in the digital multichannel TV broadcasting, in which the number of programs can be changed at any time, it is necessary to display program guide information on the screen of a digital TV set, so that user can select one from among several programs. For this purpose, the ATSC standard provides for a unique electronic program guide (EPG) for program selections. That is, TV broadcast stations transmit EPG information on every RF channel, and digital TV sets receive and store the EPG information so as to display it on a screen when requested by user.
The user can check the list of programs transmitted through subchannels of a certain RF channel by means of such EPG information, but the user must check an extra EPG information screen for that purpose. Therefore, when programs of subchannels are changed, a user can not be immediately advised thereof.
As aforementioned, it is a drawback of the prior art that a user misses useful desired programs because the user can not be immediately informed of changed programs of subchannels in digital multichannel TV broadcasting.